In the field of telecommunications, messaging services are very widely used.
In particular, most telecommunications operators offer their subscribers a voice messaging service. If a subscriber having this service cannot be reached, for example if his terminal is switched off or outside network coverage, if his line is busy or unconditionally switched to voice messaging, or if the user simply refuses to take the call, the caller wishing to reach the subscriber can then record a voice message in a voice messaging mailbox offered by the telecommunications operator to which the subscriber is signed up. This messaging service then notifies the subscriber of the presence of a new message in his voice messaging mailbox.
Some telecommunications operators also offer their subscribers a multimedia messaging service. This service can be used, notably, to receive large messages containing images, sound, text or video. This type of service is provided by a multimedia messaging server which enables multimedia messages to be transmitted from and received at any communication terminal comprising a suitable communication interface for communicating with the multimedia messaging service, and a multimedia message composition and reading interface. This service may be deployed on any type of fixed or mobile communications network, such as the internet, administered by the telecommunications operator to which the subscriber has signed up.
A drawback of the aforesaid messaging services is that they are very highly integrated into the infrastructure of the telecommunications operators who offer them. For this purpose, voice or multimedia messaging servers have special interfaces which communicate with devices in the architecture of the telecommunications network administered by the telecommunications operator, such as the HLR (Home Location Register) database which stores the subscriber identification information, the VLR (Visitor Location Register) database which temporarily stores the data on all the subscribers belonging to the geographic surface controlled by this architecture, or possibly the AuC (Authentication Centre) which is responsible for checking whether or not a service offered by a telecommunications operator is requested by an authorized subscriber.
Therefore, if the subscriber has contact identifiers other than a contact identifier assigned by the subscriber's telecommunications operator, such as a mobile or fixed telephone number, the telecommunications operator is unable to allocate a messaging mailbox associated with these other contact identifiers which it does not itself manage. Examples of other such contact identifiers include a SIP (Session Initiation Protocol) address, a WebRTC (Web Real-Time Communication) identifier, an instant messaging identifier, and others.
Usually, therefore, the subscriber has to disclose the contact identifier assigned to him by his telecommunications operator to anyone wishing to contact him, in order to benefit from a messaging service.
This results in a lack of flexibility in the use of existing messaging services.
Moreover, these messaging services are wholly unsuitable for the implementation of some services, notably communication services which protect the anonymity of a user who wishes to send or receive a message from his communication terminal. For this purpose, these communication services offer to allocate a secondary contact identifier to the terminal of the user, who already has a main contact identifier. For example, if the user has a mobile communication terminal, the main contact identifier is an MSISDN (“Mobile Station International Subscriber Directory Number”) identifier, which corresponds in a unique manner to the SIM (“Subscriber Identity Module”) card that is provided by the operator of the mobile network to which the user subscribes. More generally, a main contact identifier is assigned by the telecommunications operator to which the user subscribes. These anonymity protection services are offered, for example, when the user wishes to place an announcement on a dedicated internet site for this purpose, such as a small ads site, a dating site, a personal or professional social network, or the like. The user is then offered the chance to benefit from a secondary contact identifier which is not linked to the telecommunications operator to which the user has subscribed, and which enables the user to use this secondary contact identifier to communicate with any person who has left their details on the dedicated website, without the need to disclose the user's main contact identifier to this person.
The user of the anonymity protection service can be reached equally well on this secondary contact identifier. However, if the user does not respond to a communication made to his secondary contact identifier, because his terminal is switched off or outside network coverage, or because he does not wish to reply to the communication, or because he is on line, the caller is unable to leave a message in a messaging mailbox associated with this secondary contact identifier. At best, the anonymity protection service may offer conditional call forwarding to a messaging mailbox associated with the main contact identifier of the user of the anonymity protection service. In the last-mentioned case, the welcome message of the messaging mailbox may disclose the name or the main contact identifier of the user of the anonymity protection service, thus making this service entirely useless.